Performance Evaluation of the Biological Diagnosis of HIT

Inclusion criteria : * Adult patient (≥ 18 years of age) * Hospitalized at HUS between 01/01/2009 and 31/12/2019 * Specimen sent to the HUS Hematology Laboratory for biological diagnosis of HIT between 01/01/2009 and 31/12/2019 * Data collected by the CRPV and analyzed by the HIT multidisciplinary group in order to reach a consensus decision on the presence or absence of HIT * Patient does not object to the reuse of his medical data for scientific research purposes. Exclusion criteria: * Patient for whom no test has been performed at the HUS Hematology Laboratory * Patient for whom no data has been collected by the CRPV * Patient for whom the HIT group could not confirm or deny the presence of HIT